According to prior art, crimping machines are used for making various crimp connections and for joining pieces by crimping, in which machines the crimping tool comprises several jaw segments which are placed in a circular array and are movable radially in relation to the work piece to be machined and the centre of the crimping tool. In this description, the term jaw will also be used for referring to a jaw segment.
The piece to be machined by said crimping machine is typically a connector, known as such, which is clamped around a flexible hose to make a tight fitting. Part of the structure of the connector is also fitted inside the hose.
For making the crimp connection, the hose and the connector are joined and placed in an opening in the centre of the crimping machine, after which the jaws are used to perform crimping from several radial directions towards the centre of the crimping tool. The number of jaws may be 8 or more, normally an even number, and they are normally placed two by two on opposite sides of the work piece. The jaws normally cover an equal share of the circular shape, and they are normally placed at substantially even intervals on the circle. The crimp connection is based on a deformation of the work piece, whereby the diameter of the outermost part, for example collar, of the connector placed around, for example, a flexible hose is reduced, pressing the hose tightly between an inner part and the outermost part of the connector.
The opposite jaws, as a pair, delimit the minimum and maximum diameter of the opening left between them. The jaws determine the minimum diameter of the opening, when the adjacent jaws are tightly against each other and the radial movement towards the centre of the opening has been completed. With openings larger than this, the jaws can be apart from each other, and it is possible to perform crimping by applying a desired force effect. Forces, which are preferably equal in magnitude, are effective on the work piece from radial directions and cause the desired deformation, by means of which it is possible to connect different parts of the work piece to each other.
The position of the jaws or the size of the opening is measured either directly or indirectly, in order to know the size of the opening in each situation and at different stages of crimping. The measurement can be taken from a mechanism that moves the jaws, or from an actuator effective on the jaws or said mechanism. This is typically the measurement of the position. During crimping, the size of the opening is monitored, and the crimping is ended after a predetermined opening size or measurement has been achieved. Said predetermined opening size or measurement is selected according to the type of the work piece, the size of the work piece, the materials, or other parameters relating to the work piece or objectives for the crimping process or the desired deformation.
The above presented crimping machines can also be used for making corrugations, reductions and other deformations, for example, at the ends of tubes. A crimping machine of prior art for making various crimp connections and for joining pieces by crimping is disclosed in document EP 1230716 A1.
The operation of the jaws of the crimping machine is based on various mechanisms. The jaws are functionally coupled to a mechanism that forces the jaws to move simultaneously and in the radial direction. It may be a mechanism in a single piece or in several pieces, comprising wedge-like counter surfaces or guiding surfaces or moving in a direction perpendicular to a line extending through the centre of the opening. It may also be an annular or circumferential wedge mechanism based on, for example, one or two cones moving in parallel with the line extending through the centre of the opening. The jaws and the mechanism are moved by one or more actuators which are typically cylinder actuators driven by pressurized medium. The actuator exerts a force effect on the work piece by means of the jaws and the mechanism.
After the crimping process, the work piece is removed from the crimping machine and is subjected to a verifying measurement. The purpose of the verifying measurement of the work piece is, apart from quality control, to control that the final size of the work piece after the crimping, particularly its diameter, corresponds to a predetermined size or measurement. Said final size will depend on the size of the opening of the crimping machine that was achieved at the end of the crimping. In prior art, the control has been made in a separate measuring device, so that it is obvious that the verifying measurements take time, cause delays and increase the number of work stages. These work stages delay the readjustments and corrections that need to be made in the settings of the crimping machine and its control system so that the final size of the work piece and, at the same time, the resulting crimp connection would meet the requirements set for a work piece and a reliable crimp connection. Because a separate verifying measurement is not taken for each work piece, a production batch of work pieces may also contain defective work pieces.
Particularly in the case of crimp connections that will be subjected to pressure loading, it is vitally important that the connections are leak-free and safe. It should also be possible to make quick changes in the settings of the crimping machine and its control system, to prevent the production of defective work pieces or to significantly reduce their number. It is also important to detect significant changes in the crimping process in time.